Semiconductor wafers for semiconductor and optoelectronic applications are conventionally separated into individual dice by cleaving along a preferential crystal orientation. Cleaving is promoted by forming scribe lines or edge nicks in the material to generate a fracture location. Compound III-V semiconductor materials are commonly used in the fabrication of integrated circuits and optoelectronic devices, e.g. lasers and optical amplifiers. Such optoelectronic devices conventionally have a Fabry-Perot cavity wherein high quality cleaved end surfaces serve as the cavity mirrors. Alternatively, distributed feedback (DFB) or distributed Bragg reflector (DBR) type lasers, or other devices such as semiconductor Mach Zehnder modulators may also require optical quality cleaved facets. There may be as many as 10,000 devices on a 1" diameter wafer. After defining device structures, the semiconductor wafer is separated into individual elements by cleaving. A high yield at the cleaving stage is critical.
The wafer is usually cleaved into quarters which are subsequently cleaved into bars wherein each bar contains a plurality of side-by-side devices. These bars are then cleaved to separate the individual elements.
The cleaving process is traditionally a manual operation with a skilled operator using a probe to initiate crack propagation within either a scribed laser bar or a wafer quarter. This is labour intensive process and the yield of good devices is often dependent on the skill and ability of the operator. Further, as new and different laser structures are introduced into production or as production volumes increase more operators are required to meet the increased workload. It is difficult to control and ensure the consistency of a purely manual skill, even with a small workforce. As extra staff is introduced to the operation, additional training and close monitoring is required.
Accordingly, there is a need in the industry for alternative methods of cleaving semiconductor wafers which would avoid manual operation and provide high yield of laser devices with high quality cleaved facets.